In recent years, many types of curved glass sheets have been employed as windowpanes for automobiles. Such curved glass sheets are each produced by cutting a flat plate-shaped glass sheet produced by e.g. a float process to have a desired shape and size, heating the glass sheet up to the softening point (about 650° C.) and e.g. a press-molding it into a desired curved shape. Then, the glass sheet molded to be curved is brought to a shape inspection as follows.
FIG. 9 shows a conventional shape inspection apparatus for curved glass sheets. As shown in the figure, an inspection apparatus 100 comprises an inspection plane 101 on which a glass sheet G is placed and which is shaped to have a curved shape corresponding to the shape of the glass sheet G to be inspected, in advance. In the inspection plane 101, a plurality of displacement sensors 102 are embedded. Therefore, when a glass sheet G is placed on the inspection plane 101, the distances (displacement amounts) from the inspection plane 101 to the bottom surface of the glass sheet G are measured by the displacement sensors 102, and the measurement results are read out by a controller 200. As a result, the controller 200 judges that the glass sheet is a good product if the displacement amounts are within a predetermined range (for example, within ±0.5 mm), and judges that it is a defective product if the displacement amounts are not within the range.
Thus, in the conventional inspection apparatus 100 shown in FIG. 9, the shape of the inspection plane 101 needs to be newly prepared according to the model of glass sheet G, and the plurality of displacement sensors 102 need to be newly embedded according to e.g. the shape of glass sheet G. Therefore, a dedicated inspection apparatus 100 needs to be prepared for every model of glass sheet G, and there has been a problem that the cost for the inspection is increased. Since a plurality of curved glass sheets such as a windshield, a rear glass, a door glass, a front bench, and a rear quarter are employed for each automobile, it is necessary to prepare a dedicated inspection apparatus 100 for each of them. Further, since it is necessary to prepare the set of inspection apparatuses 100 for each automobile model, a huge number of inspection apparatuses 100 become necessary.
It is an object of the present invention to resolve the above-mentioned problems, and to provide a method of and an apparatus for inspecting a curved shape whereby the same inspection apparatus can be used regardless of the difference of the model of the glass sheet, and the inspection can be performed more easily than the conventional methods and apparatuses.